- Table of Contents
-
- 04-Layer 3—IP Services Configuration Guide
- 00-Preface
- 01-ARP configuration
- 02-IP addressing configuration
- 03-DHCP configuration
- 04-DNS configuration
- 05-IP forwarding basics configuration
- 06-Fast forwarding configuration
- 07-Adjacency table configuration
- 08-IRDP configuration
- 09-IP performance optimization configuration
- 10-UDP helper configuration
- 11-IPv6 basics configuration
- 12-DHCPv6 configuration
- 13-IPv6 fast forwarding configuration
- 14-Tunneling configuration
- 15-GRE configuration
- 16-HTTP redirect configuration
- Related Documents
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Title | Size | Download |
---|---|---|
05-IP forwarding basics configuration | 60.60 KB |
Contents
Configuring IP forwarding basic settings························································ 1
About FIB table······························································································································· 1
Saving the IP forwarding entries to a file··························································································· 2
Display and maintenance commands for FIB table············································································ 2
Configuring load sharing··················································································· 3
About load sharing·························································································································· 3
Configuring load sharing mode········································································································ 3
Enabling local-first load sharing······································································································· 3
Enabling symmetric load sharing······································································································ 4
Configuring IP forwarding basic settings
About FIB table
A device uses the FIB table to make packet forwarding decisions.
A device selects optimal routes from the routing table, and puts them into the FIB table. Each FIB entry specifies the next hop IP address and output interface for packets destined for a specific subnet or host.
For more information about the routing table, see Layer 3—IP Routing Configuration Guide.
Use the display fib command to display the FIB table. The following example displays the entire FIB table.
<Sysname> display fib
Destination count: 8 FIB entry count: 8
Flag:
U:Usable G:Gateway H:Host B:Blackhole D:Dynamic S:Static
R:Relay F:FRR
Destination/Mask Nexthop Flag OutInterface/Token Label
0.0.0.0/32 127.0.0.1 UH InLoop0 Null
127.0.0.0/8 127.0.0.1 U InLoop0 Null
127.0.0.0/32 127.0.0.1 UH InLoop0 Null
127.0.0.1/32 127.0.0.1 UH InLoop0 Null
127.255.255.255/32 127.0.0.1 UH InLoop0 Null
224.0.0.0/4 0.0.0.0 UB NULL0 Null
224.0.0.0/24 0.0.0.0 UB NULL0 Null
255.255.255.255/32 127.0.0.1 UH InLoop0 Null
A FIB entry includes the following items:
· Destination—Destination IP address.
· Mask—Network mask. The mask and the destination address identify the destination network. A logical AND operation between the destination address and the network mask yields the address of the destination network. For example, if the destination address is 192.168.1.40 and the mask 255.255.255.0, the address of the destination network is 192.168.1.0. A network mask includes a certain number of consecutive 1s. It can be expressed in dotted decimal format or by the number of the 1s.
· Nexthop—IP address of the next hop.
· Flag—Route flag.
· OutInterface—Output interface.
· Token—MPLS Label Switched Path index number.
· Label—Inner label.
Saving the IP forwarding entries to a file
Restrictions and guidelines
The feature automatically creates the file if you specify a nonexistent file. If the file already exists, this feature overwrites the file content.
This feature triggers one-time saving of the IP forwarding entries.
To automatically save the IP forwarding entries periodically, configure a schedule for the device to automatically run the ip forwarding-table save command. For information about scheduling a task, see Fundamentals Configuration Guide.
Procedure
To save the IP forwarding entries to a file, execute the following command in any view:
ip forwarding-table save filename filename
Display and maintenance commands for FIB table
Execute display commands in any view.
Task |
Command |
Display FIB entries. |
display fib [ vpn-instance vpn-instance-name ] [ ip-address [ mask | mask-length ] ] |
Configuring load sharing
About load sharing
If a routing protocol finds multiple equal-cost best routes to the same destination, the device forwards packets over the equal-cost routes to implement load sharing.
Configuring load sharing mode
About this task
In the per-flow load sharing mode, the device forwards flows over equal-cost routes. Packets of one flow travel along the same routes. You can configure the device to identify a flow based on the following criteria: source IP address, destination IP address, source port number, destination port number, IP protocol number, and ingress port.
In a complex network, when the traffic is not load shared equally, you can use the algorithm keyword to specify an algorithm to improve the load sharing.
Feature and software version compatibility
This feature is available in Release 1107 and later.
Procedure
1. Enter system view.
system-view
2. Configure load sharing.
ip load-sharing mode { per-flow [ dest-ip | dest-port | ingress-port | ip-pro | src-ip | src-port ] * } { global | slot slot-number }
By default, the device performs load sharing based on the source IP address, destination IP address, source port, destination port, IP protocol number and ingress port of a packet.
3. Display the load sharing path selected for a flow.
display ip load-sharing path ingress-port interface-type interface-number packet-format { ipv4oe dest-ip ip-address [ src-ip ip-address ] | ipv6oe dest-ipv6 ipv6-address [ src-ipv6 ipv6-address ] } [ dest-port port-id | ip-pro protocol-id | src-port port-id | vpn-instance vpn-instance-name ] *
The option settings in this command must match both the options displayed in the display ip load-sharing mode command and the field values in load shared packets. If the option settings do not meet the requirement, the path displayed by this command might be different from the real path for load sharing.
Enabling local-first load sharing
About this task
Local-first load sharing distributes traffic preferentially across the output interfaces on the receiving IRF member device if output interfaces for multiple equal-cost routes are on different members. This feature enhances packets forwarding efficiency.
Procedure
1. Enter system view.
system-view
2. Enable local-first load sharing.
ip load-sharing local-first enable
By default, local-first load sharing is enabled.
Enabling symmetric load sharing
About this task
Symmetric load sharing ensures that bidirectional traffic specific to a source and destination address pair flow along the same path.
Feature and software version compatibility
This feature is available in Release 1107 and later.
Procedure
1. Enter system view.
system-view
2. Enable symmetric load sharing.
ip load-sharing symmetric enable
By default, symmetric load sharing is disabled.